As a founder of the Byrds and a long-standing member of Crosby, Stills, Nash and Young, David Crosby can claim to be rock ‘n’ roll royalty.

His musical accomplishments, though, are overshadowed by a personal history that features three heart attacks, a liver transplant, diabetes and epic drug addictions which in 1983 earned him a five-years sentence in a Texas prison.

Now 78 years old, estranged from his former bandmates and still touring to keep a roof over his family’s head, Crosby looks back on his life and career in “David Crosby: Remember My Name,” the first feature documentary from director A.J. Eaton.

The film has a solid first hour, then loses focus and sort of drifts off in its final 30 minutes.

Still, there is much to admire here, for this is no warm dip into fuzzy nostalgia. The white-haired Crosby comes off as brutally honest about his failures: “Big ego. No brain.”

He was, he admits, a massive jerk. Only after his legal comeuppance forced him to go cold turkey in a jail cell did he get his life in order; he reports that until his stint in prison he had never performed straight. Not once.

In matters of sex, he recalls, “I was a caboose to my dick…there are borders I’ve crossed you’ve never heard of.”

The son of Hollywood cinematographer Floyd Crosby (“High Noon”), young David grew up in an emotionally stifled environment. Rock music was his salvation.

The doc features vintage footage of the mid-60s Byrds in performance; Crosby’s main contribution was an unerring ear for vocal harmonies.

“Aloha” can mean either hello or goodbye. Thus it’s an appropriate title for a movie that doesn’t know if it’s coming or going.

That the latest from writer/director Cameron Crowe isn’t a total disaster can be credited to players whose charisma helps paper over the screaming holes and loopy notions marring the doddering screenplay.

These performers are just good enough to wrest a few memorable moments from the general chaos of an eccentric romantic comedy that isn’t particularly romantic or funny.

Brian Gilcrest (Bradley Cooper) is a near-legendary former Air Force officer who was deeply involved in the U.S. space program. But after a long career decline and injuries incurred while a contractor in Afghanistan, he’s now a mere shadow of his former self.

He’s returned to his old stomping grounds in Hawaii as an employee of multi-billionaire Carson Welch (Bill Murray), who has invested heavily in a private rocket program and needs the blessing of native Hawaiian leaders to pave over some public relations potholes.

Brian’s assignment is too look up his old friend, the king of the nativist Nation of Hawaii (Dennis Bumpy Kanahele, playing himself), and secure said blessing.

Meanwhile Brian is torn between two women. First there’s Tracy (Rachel McAdams), the love he unceremoniously dumped 13 years earlier. She’s now married to an Air Force Officer (John Krasinski) and the mother of two.

The arrival of her old flame — even in his semi-decrepit condition — exacerbates Tracy’s doubts about her marriage and a husband whose verbal communications are painfully limited.

The other woman is Allison Ng (Emma Stone), a hotshot fighter pilot and one-quarter Hawaiian who is assigned as Brian’s military escort. Allison starts out all spit and polish with a salute so sharp it snaps air molecules — but after a few days as Brian’s wingman her military bearing turns all gee-whiz girly.